[Bromine cloud in Geneva. Epidemiologic study of the short-term effects on a population sample].

In November 1984, due to an accident at a chemical plant, toxic bromine gas spread into the town of Geneva, Switzerland, at concentrations over five times the maximal admissible concentration (MAC). Monitoring of atmospheric brome concentrations allowed the determination both of the duration of exposure and the geographical area concerned. Description of the immediate measures taken at the time of the accident illustrates how mass panic reactions can be generated or controlled, and clearly shows the vital importance of an effective communication network: it was lacking in this case and caused further insecurity for the population and isolation of the hospital. Immediate and systematic data collection enabled us to carry out an "acute" epidemiological survey of the accident. It is the first report of mass bromine intoxication in the medical literature. 91 patients with symptoms of bromine exposure were seen in the outpatient and casualty departments of the cantonal Hospital, but the clinical course was mild and self-limited in nearly all cases. One patient was admitted for 24 hours. The most common symptoms were upper respiratory tract symptoms, cough and headache. In 20-30% of cases these pesisted for more than three days, and sometimes up to one month. Recording the location of patients at the time when their first symptoms occurred made it possible to define the exposed area with precision. When the initial data collected in this "acute" fashion is reliable, it should be possible to undertake more elaborate epidemiological studies at a later stage if necessary.